Long-term sequelae of bronchiolitis induced by nitrogen dioxide in hamsters

The long-term consequences of acute lung injury during critical growth periods of the lung were evaluated by inducing mild bronchiolitis with nitrogen dioxide (NO2) in 3-day-old (newborn) and 21-day-old (young) hamsters. Hamsters were exposed to 30 ppm NO2 for 7 days. Age-matched animals exposed to room air served as controls. Lung volumes, static deflationary pressure-volume curves, mean linear intercept, and internal surface area were measured when the animals reached 1 yr of age. Newborns exposed to NO2 showed an increased volume at 25 cm H2O pressure (V25) adjusted for body weight, a decreased transpulmonary pressure at 60% of V25, and an increased mean linear intercept when compared with control animals. The internal surface area was less than that in the control animals; the difference approached significance. In the young exposed group there were no differences for any measurements when compared with the control group. These data indicate that a mild injury imposed during the newborn period may result in physiologic and morphometric changes that simulate mild emphysema in the mature animal.